98 Clarence J. Elmore 



In creeks, rivers, ponds, etc., among higher algae, also fossil: Benkle- 

 man, Brownlee, Burge, Central City, Crawford, Culbertson, Dismal River, 

 Dunning, Johnson, Gordon Creek, Grand Island, Hackberry Lake, Halsey, 

 Holt County, Hyannis, Lincoln, Long Pine, Louisville, New Helena, North 

 Platte, Omaha, St. Paul, Scottsbluff, Seneca, Stanton, Stromsburg, Teka- 

 mah, Trenton, Valentine, Wann. 



Fossil: Agate, Loup City, Merriman, Spalding, Valentine. 



Little White River, Weta, S. Dak. ; Stockton, Cal. ; Ft. Collins, Colo. 



2^. Achnanthes 



Achnanthes Bory. Diet. Class., I, p. yp, 393. 1822. 



Etym. from Gr. a.x^r], point, and a.v6o<i, flower. 



Cells single or forming short chains attached by the basal cell, 

 cells curved in girdle view; valves elliptical to lanceolate, often 

 broader or narrower in the middle ; valves dissimilar, the one con- 

 cave with a true raphe and central and terminal nodules, the other 

 convex with a pseudoraphe ; both valves striate with transverse 

 rows of dots, sometimes ribbed. 



A. Lower valve with a pseudostauros. i. A. hungarica. 

 AA. Lower valve without a pseudostauros. 



b. Upper valve dififering from the lower only in the absence of raphe 

 and nodules. 

 c. Apices capitate. 



d. Narrowly lanceolate. 2. A. microccphala. 



dd. Gibbous in the middle. 3. A. biasolettiana. 



cc. Apices not capitate. • 4. A. linearis, 

 bb. Upper valve with a borseshoe-shaped hyaline space next to one 



margin in the middle. 5. A. lanccolata. 



I. Achnanthes hungarica Grun. in CI. & Grim. Arct. Diat., p. 20. 

 1880. 



PI. 13, figs. 483-487; pi. 23, fig. 844. 



Narrowly elliptic or linear-lanceolate with ends more or less 

 cuneate or rounded, 15-43 /a long, 6-8 /x, wide; upper valve with a 

 narrow axial area, the two middle striations shortened ; lower valve 

 with raphe along which is a narrow hyaline space, central striations 

 lacking, leaving a pseudostauros; striations slightly radiate, 18-21 

 in iO;Li; cells geniculate or, when in longer chains, nearly straight, 

 as in fig. 844. 



In creeks, rivers, ditches, ponds, etc., also fossil : Anselmo, Broken 



